Nigeria's military said it has rescued women and children taken hostage by the rebel group Boko Haram after an attack on a police barracks.

The claim on Friday by the country's defence department could not be independently confirmed.

"Nigerian troops have rescued three women and six children from Boko Haram in the Sambisa forest in Borno state, in northern Nigeria," said a statement from the defence department.

"The women and children were kidnapped by the group on May 7 following an attack on police barracks in Bama. Thousands of soldiers are involved in an offensive against Boko Haram in region that's been going on for 10 days"

Brigadier General Chris Olukolade said the army freed the group who had been in a propaganda video by the Boko Haram.

A Boko Haram video seen by The Associated Press earlier in May showed 12 young boys and girls.

Olukolade said extremists took the hostages after a May 7 attack on the town of Bama. He said a woman and her two children remain missing.

Nigeria has faced increasingly bloody attacks by extremists since 2010. President Goodluck Jonathan declared emergency rule in three northeastern states May 14, giving security control to the military.

Source: Al Jazeera and agencies